In my experience no WAY man!... i have a EP600 that i had to have the amp serviced on... So while it was away i was using 2 8" JBL subs that i have around the house.... When the 600 was back in service... Holy Moly...a night and day difference comparison would not be adequate. I have retained one of the 8" JBL's to work in conjunction with the 600. However, you can not even hear the 8"... The only way i know it's working is the Green LED, and also by feeling the driver moving... The 600 is overpowering the 8" by that much.... I think that the little 8" is probably adding something to the room though, it's got to right?

I can not speak to a comparison of 2 ep500's as compared to 1 600/800 though... as the 500's are much larger than my little 8" JBL subs...